Topological susceptibility in two-flavor lattice QCD with exact chiral symmetry

S. Aoki; T. W. Chiu; H. Fukaya; S. Hashimoto; T. H. Hsieh; T. Kaneko; H. Matsufuru; J. Noaki; K. Ogawa; T. Onogi; N. Yamada

doi:10.1016/j.physletb.2008.06.039

paper

Topological susceptibility in two-flavor lattice QCD with exact chiral symmetry

arXiv:0710.1130 · doi:10.1016/j.physletb.2008.06.039

Abstract

We determine the topological susceptibility $χ_{t}$ in two-flavor QCD using the lattice simulations at a fixed topological sector. The topological charge density is unambiguously defined on the lattice using the overlap-Dirac operator which possesses exact chiral symmetry. Simulations are performed on a $1 6^{3} \times 32$ lattice at lattice spacing $\sim$ 0.12 fm at six sea quark masses $m_{q}$ ranging in $m_{s} /6$ -- $m_{s}$ with $m_{s}$ the physical strange quark mass. The $χ_{t}$ is extracted from the constant behavior of the time-correlation of flavor-singlet pseudo-scalar meson two-point function at large distances, which arises from the finite size effect due to the fixed topology. In the small $m_{q}$ regime, our result of $χ_{t}$ is proportional to $m_{q}$ as expected from chiral effective theory. Using the formula $χ_{t} = m_{q} Σ/ N_{f}$ by Leutwyler-Smilga, we obtain the chiral condensate in $N_{f} = 2$ QCD as $Σ^{MS ˉ} (2GeV) = [252 (5) (10) MeV]^{3}$ , in good agreement with our previous result obtained in the $ε$ -regime.

arXiv comment11 pages, 3 figures, v2: accepted for publication in PLB

Topological susceptibility in two-flavor lattice QCD with exact chiral symmetry

Abstract

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